Several questions concerning the general circulation for which satisfactory answers are not yet available are discussed. The focus is on the zonal mean heat balance, since problems in our understanding of this balance are a fundamental limitation on our ability to model climate and climate change. The questions are: How strong is the atmosphere's poleward heat transport? What are the relative roles of large-scale eddies and small-scale convection in stabilizing the mid-latitude atmosphere? What are the dynamical mechanisms that maintain the time mean zonal mean state in mid-latitudes? Some suggestions for addressing these questions are given.

© 2008 Elsevier